Explosion resisting lighting unit



Aug. 11, 1936. H. P. HASTINGS 2,050,839

EXPLOSION RESISTING LIGHTING UNIT Filed Oct. 22, 1952 2 Sheets-Sheet 1 7 3% l/, aa 9, as 36 i /s g 7 J/g; Z

INVENTOR.

ATTORNEYS.

Aug. 11, 1936. H. P. HASTINGS 2,050,839

EXPLOSION RESISTING LIGHTING UNIT Filed Oct. 22, 1932 2 Sheets-Sheet 2 IN VEN TOR.

ATTORNEYS.

STTS

EXPLOSION RESISTING LIGHTING UNIT Harold P. Hastings, Syracuse, N. Y., assignor to Grouse-Hinds Company, Syracuse, N. Y., a corporation of New York Application October 22, 1932, Serial No. 639,084

2 Claims.

This invention relates to what for convenience is called explosion resisting lighting units, and has for its object a construction by which heated gases from the explosion occurring within the lighting unit can not communicate with and ignite explosive vapors that may be present outside of the lighting unit and cause disastrous explo- S10I1S. r

It has been found practically impossible to make an absolutely vapor-proof fitting or lamp which will prevent outside vapors from finding their way inside of the lighting unit or the globe thereof. So-called vapor-proof fittings that are satisfactory or practically vapor-proof in some situations are not vapor-proof in others, especially where the highly explosive vapors, as gasoline vapors, are present, and the object of this invention is a lighting unit which confines the .explosion, where it originates inside of the unit,

so that the exploded gases before they find their way outside the unit are cooled below the ignition point of any explosive vapors that may be pres- .ent in the surrounding atmosphere.

A further object of this invention is the provision of metal to metal, or metal to glass, joints throughout the construction, whereby such joints 1 may be machined accurately and thus retard the escape of the ignited gas until the same has been cooled below the ignition point. -Such a joint, while not necessarily vapor-tight, may be described as flame-tight, or explosion proof.

Another object of the invention is provision for relamping the fixture without disassembling any of the joints thereof that would require any particular care in reassembling them, in order to maintain the flame-tight joint and the efficiency of the lighting unit. j

The invention consists in the novel features and in the combinations and constructions hereinafter set forth and claimed.

In describing this invention, reference is had to the accompanying drawings in which like characters designate corresponding parts in all the views.

Figure 1 is an elevation, partly in section, of

. this lighting unit.

Figure 2 is an enlarged elevation,-taken at difierent angle from Figure 1.

Figure 3 is a vertical, or lengthwise sectiona View, of a slightly modified form of this lighting unit on the plane of line 3-3 Figure 4.

m Figure 4 is a plan view looking upward of the globe support shown in Figure 3.

This lighting unit comprises generally a hollow base having means for connection to an electric conduit system enclosing service wires, which service wires enter the hollow base for connection to the terminals of a lamp socket, a lamp socket mounted on or within the base and so arranged as to form a well for receiving a sealing 5 medium in which the portion of the lamp socket in the base, its wire terminals, and the contiguous portions of the wires, are embedded, a globe support coupled to the base around the lamp socket, a globe carried by the support, means for securing the globe to the support, and means for preventing detachment of the globe from the support, while the support is coupled to the base, there being a vapor-proof and flame-tight joint between the globe and its support and also a flame-tight joint between the support and the base being such as to bafiie the outlet of exploded port is coupled to the base, is for the purpose of requiring a workman when changing the lamp bulbs to remove the globe and its support, as a unit, and making it impossible to disturb the vapor-proof and. flame-tight joint between the globe and its support by removing the globe from its support. This joint is initially made vaporproof at the factory and it is not intended to be disturbed by a workman who in exchanging the lamp might leave it loose or defective so that it would not be vapor-proof, or flame-tight.

l designates the base, which is here shown as :bell-shaped-in form, and having means as an internally threaded nipple 2 at its upper end for connection to an electric conduit, not shown, en- ,closing the service wires. shown, is also provided with a work hole 3 in one side,-which is normally closed by a closure or plug 4. This work hole is for the purpose of The base, as here splicing the wires of the lamp socket to the serv- ,;ice'wires.' The; base i is provided with a hub portion 5 at its lower end in which a lamp socket base 6 is mounted, the inner end portion of the lamp socket extendinginto the hub, and the hub The screws H are provided with break-off heads so that the lamp socket can not be disturbed after it is once in position. Y 7 l2 designates the globe support, and I 3 the globe. The support I2 is also shown as bellshaped in general form and as threaded at l4 on the hub 5 of the base. The globe l3 may be of glass, or other transparent material, and is formed sufi'iciently thick or heavy to resist explosions of the thin vapors that work their way into the interior of the globe. The means for securing the globe to its support is here shown as an annular metal ring 2| formed on the upper end of the guard or cage 22, and provided with an inwardly extending flange 23 which engages the under side of an outwardly extending flange 24 at the upper edge of the globe I3. Preferably, yielding gaskets, or Washers, 25, 26, are interposed between the upper face of the 'flange 24 and the abutting face 21 of the flange '28 of the support 2, and between the lower face of the flange 24 and the supporting flange -23;

In order to provide a metal to metal, or metal to glass contact, the gasket 25 is metal covered. This metal covering 29 is formed U shaped in cross section, firmly Securing the gasket 25 to the upper face of the flange 24, and also securing the cushioning gasket 26 to the under side of the flange 24. The'ring 2|, guard 22, globe I3,

and gaskets 25, 26, areall secured to the support |2 by means of a plurality of screws 30 passing through the support |2 from the top thereof, and threading into the annular ring 2|, or into bosses formed thereon. The holes 3|, through which the screws 30 pass, are counterbored at the outer end into which counterbores the heads of the screws Snare seated. In the structure shown in Figure 3, these counterbores arefilled with 'seali-ng compound 32 after the screws-have been threaded into the ring 2|. The object of this procedure is'to prevent accidental or unnecessary removal of the ring 2| from the support 12 by inexperienced persons. In the structure shown in Figure 1, the screws are not sealed with compound. ;However, it is impossible to remove the screws 30 without first having unscrewedth'e support |2 from the base due'to the fact that the shade 33 extends over the counterbores in which the screws 33 are located. Inasmuch as the guard 22 is formed integral with, or secured by the ring 2|, the guard is firmly secured to" the support |2 together with theglobe and gaskets.

The provision of-a flame-tight metal to metal, or metal to glass joint, Figure 3, between the globe l3 and the support I2 is most essential in a fitting of this type. Themethod of forming the metal covering 29, Figure l, and -'29 -Figure 3, on the flange 24 of theglobeconstitutesaseparate invention and does not form part of this application. The -metal coverings 29, 23 are rings u shaped in cross-section, and-the covering 2'9 has reentrant flanges -29 between which and the branches of the U formation the gaskets 25, 26, are located.

After the globe is provided with the gaskets 25 26, and the metal covering 29,-a high degree of skill is not required to establish a. flame-tight joint between the globe and the support 12. However,-it has been found in'p'ractice that the average person in relamping afixture of this type, and in most'cases not appreciatingthe necessity of a flame-tight joint,- does note'xercisesuflicient care in securing the ring 2| to'the support I'Zand thereby securing the globe to the support. 7 It is chiefly-because of this factthat the fixture is provided with means whereby "the support 2, guard 22, andglobe |3, are removed asa fromthe base whenthe fixture is-re'lampe'd. The l shieldor renetor '33 igand the sealing compound 32, Figure 3, prevent accidental or unnecessary removal of the screws 30. The reflector 33 is secured to the base by means which are inaccessible when the support is coupled to the base I. As here shown, the reflector is provided with an internal annular flange 34 lapping a downwardly facing shoulder 35 on the base and the shield, or reflector, is secured in position by screws 36 threading through the flange and into the shoulder on the base, the heads of the screws being opposed to and obstructed by the support i2 when coupled to the base In Figure 3, the hub portion 5 of the base is of sufficient length to provide an abutment for the set screw ll! which threads through the wall of the support -'|-2. The'purposeof this set screw is to prevent the support |2 from loosening on the base due to vibration inherent in certain uses such as when'the lighting fixture is secured to the top of an oil well derrick.

:Initially,'-the parts are assembled at the factory and noneof *the joints are intended to be interfered with by workmen except that the workmen can detach the-support l2, globe |3, and the guard 22, from the base asa unit, without disturbing 25 vapor-tight joints accurately made at the factory. When the is installed in a place where volatile vapors are present, as for instance, gasoline vapors, the vapors will, regardless of all precautions that can be taken, find'their way into the 30 globe around the lamp bulb. If an explosion occursbyreason-of breaking the bulb, or a. sparkdue to vibration of the bulb in the socket, or for any other reason, the explosion is confined entirely withintheglobe, the glass of the globe being 35 strong enough to withstand such explosion and the joints between the U-shaped member 29 and the support l2, or between said member and the :globe j! 3, and the threaded joint between the support |2and thehub 5 of the basel are sufiiciently tight 'to prevent-the escape of the ignited gases until they have been cooled below the'ignition point, the threads-at I'd being sufficiently-numerous to require the exploded gases to take a tortu'ous path to find their way out of the'globe and support, and'in' so doing become cooled sufliciently so as not toignite' the vapors present outside of the unit.

When itis necessary to remove a lamp bulb, a workman must remove the support and'glQbe, as a unit,"by unscrewing them from the base. Because of the'relative arrangement of the shield or reflector 24,-it is impossible for him to remove the globe from its support,and hence make detective the-factory-made vapor-proof joints, and the only o'peration possible is the unscrewing of the support. After theexhausted lamp-has been 'removed andanew-lamp replaced, the globe and itssupport=are -replaced-asa unit, and owing to the threaded jointbetween the support andthe 60 base,'-a long tortuous passage is provided which obstructs-inlet of vapors from the outside of the 1 unit'- andalso obstructs and cools exploded gases when finding their way outside of the fixture.

What I claim is:

1. Inan explosion resisting lighting-unit in- "clu'din'ga hollow base havingmeans for connection to an electric conduit system enclosingthe -service wires, a lamp socke'tmounted on-said base andhaving its wire terminals located in the'base, '70

means sealin'gthednterior of the base'from-the 5 interior of the globe, a'globesupport, 'anda-g-lobe carried thereby, means for securing theglobe to -its 's'upport,-- and 5a -'vapor-proof joint'betwee'n' the -globe--and its support, the support being detach- "15 ably secured to the base by a joint operating to bafile the outlet of exploded vapors from within the globe and its support, means for preventing detachment of the globe from its support, when the support is coupled to the base, the means for preventing the detachment of the globe from its support being carried by the base, and means for securing the same to the base, the globe support being arranged to normally prevent access to said securing means.

2. An explosion resisting lighting unit including a hollow base having means for connection to an electric conduit enclosing the service wires, an external annular shoulder and a threaded axial hub below said shoulder, a lamp socket mounted at the end of the hub and extending into the hub and having wire terminals in the hub for connection to said wires, the hub and the contiguous portion of the base forming a receptacle for receiving a sealing medium surrounding the lamp socket and the wires attached thereto, a globe support threading on the hub toward said shoulder, a globe carried by the support with a vapor-tight joint between the globe and its sup port, means for securing the globe to the support, including members operable from the side of the support toward the base, means for preventing detachment of the globe from the support, when the support is mounted on the hub comprising a shield carried by the base and having a portion lapping said shoulder, and fastening screws extending through the lapping portion of the shield and into said shoulder, the heads of the screws being opposed to the support, whereby the screws are inaccessible when the support is mounted on the base, all whereby the shield can not be removed from the base while the support is coupled to the base and the globe from its support, when the support is coupled to the base.

HAROLD P. HASTINGS. 

